p-Toluenesulfonic acid → 17-Ethyl-1-hydroxy-12-[2'-(3",4"-dihydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9]octacos-14,18-diene-2,3,10,16-tetraone

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Reaction Steps

A solution of 17-ethyl-1,14-dihydroxy-12-[2'-(3",4"-dihydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9 ]octacos-18-ene-2,3,10,16-tetraone (210 mg) and a catalytic amount of p-toluenesulfonic acid in 40 ml of dry benzene was refluxed for 4 h under nitrogen atmosphere. The solvent was removed under reduced pressure and the dark brown residue was purified by column chromatography on silica gel (7% i-PrOH/CH2Cl2) to give 17-ethyl-1-hydroxy-12-[2'-(3",4"-dihydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9 ]octacos-14,18-diene-2,3,10,16-tetraone (180 mg) as a white solid. This material was dissolved in ethanol (20 ml) and treated with 5% Rh/C (40 mg). Hydrogen was introduced via balloon for 30 min and the mixture was filtered through celite. Removal of the solvent followed by column chromatography on silica gave 172 mg of the title compound (Mass, 1H and 13C NMR data were consistent with the desired structure).

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